Stylus, pressure detecting system and driving method thereof

ABSTRACT

A stylus includes a pressure detector for detecting applied pressure, a first signal generator for generating a signal of a first frequency, a second signal generator for generating a signal of a second frequency, and a controller for adjusting at least one of the first and second signal generators to control an amplitude ratio of the signal of the first frequency to the signal of the second frequency according to the applied pressure detected by the pressure detector.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2012-0030587, filed on Mar. 26, 2012, in the KoreanIntellectual Property Office, the entire content of which isincorporated herein by reference.

BACKGROUND

1. Field

Embodiments of the present invention relate to a stylus, and to apressure detecting system including a stylus and a driving methodthereof.

2. Description of Related Art

Recently, a digitizer, a touch screen, or the like, which is capable ofreplacing a conventional input device such as a keyboard and a mouse,and which is capable of directly detecting a position contacted by ahuman's hand or an object, has been widely used. In addition, the use ofa stylus system capable of performing more elaborate, or more accurate,input (as compared to a system using the human hand) tends to increase.

To perform various operations corresponding to writing pressure of thestylus acting on the digitizer (for example, a control of a thickness ofa line drawn by the stylus), desire for detection of the writingpressure of the stylus has increased. To this end, according to therelated art, a technology wherein a change in frequency of a signalemitted from the stylus corresponding to a change in pressure of thestylus, and detection of the changed frequency to sense the writingpressure of the stylus, has been used.

However, because the frequency of the signal emitted from the stylus iscontinuously changed, a frequency detection operation (for example, FastFourier transform, or the like) is repeatedly performed, therebyincreasing a processing time and complicating a hardware configuration.

SUMMARY

An aspect of embodiments of the present invention provides a stylus, apressure detecting system capable of detecting writing pressure of thestylus without changing a frequency of the signal emitted from thestylus, and a driving method thereof.

According to an exemplary embodiment of the present invention, there isprovided a stylus including a pressure detector for detecting appliedpressure, a first signal generator for generating a signal of a firstfrequency, a second signal generator for generating a signal of a secondfrequency, and a controller for adjusting at least one of the first andsecond signal generators to control an amplitude ratio of the signal ofthe first frequency to the signal of the second frequency according tothe applied pressure detected by the pressure detector.

The first frequency and the second frequency may be different from eachother.

The first and second signal generators may be respectively configured toemit the signals of the first and second frequencies through a singlesignal emitter.

The first signal generator and the second signal generator mayrespectively emit the signal of the first frequency and the signal ofthe second frequency through different signal emitters.

The controller might be configured to change an amplitude of only one ofthe signals of the first and second frequencies to control the amplituderatio of the signals of the first and second frequencies.

The controller may be configured to change both an amplitude of thesignal of the first frequency and an amplitude of the signal of thesecond frequency to control the amplitude ratio of the signals of thefirst and second frequencies.

According to another exemplary embodiment of the present invention,there is provided a pressure detecting system including a stylusincluding a pressure detector for detecting applied pressure, a firstsignal generator for generating a signal of a first frequency, a secondsignal generator for generating a signal of a second frequency, and acontroller for adjusting at least one of the first and second signalgenerators to control an amplitude ratio of the signal of the firstfrequency to the signal of the second frequency according to the appliedpressure detected by the pressure detector, and a pressure detectingapparatus for receiving the signals of the first and second frequenciesfrom the stylus, and for detecting the applied pressure according to theamplitude ratio of the signal of the first frequency to the signal ofthe second frequency.

The first frequency and the second frequency may be different from eachother.

The first signal generator and the second signal generator mayrespectively emit the signal of the first frequency and the signal ofthe second frequency through a single signal emitter.

The first signal generator and the second signal generator mayrespectively emit the signal of the first frequency and the signal ofthe second frequency through different signal emitters.

The controller might be configured to change an amplitude of only one ofthe signals of the first and second frequencies to control the amplituderatio of the signals.

The controller may be configured to change both the amplitude of thesignal of the first frequency and the amplitude of the signal of thesecond frequency to control the amplitude ratio of the signals.

According to still another exemplary embodiment of the presentinvention, there is provided a driving method of a pressure detectingsystem, the method including detecting applied pressure, controlling anamplitude ratio of a signal of a first frequency to a signal of a secondfrequency according to the detected applied pressure, emitting thesignal of the first frequency and the signal of the second frequency,receiving the signal of the first frequency and the signal of the secondfrequency, calculating the amplitude ratio of the signal of the firstfrequency to the signal of the second frequency, and calculating thepressure from the calculated amplitude ratio.

The first frequency and the second frequency may be different from eachother.

Controlling the amplitude ratio might include changing an amplitude ofonly one of the signals of the first and second frequencies to controlthe amplitude ratio of the signals.

Controlling the amplitude ratio may include changing both an amplitudeof the signal of the first frequency and an amplitude of the signal ofthe second frequency to control the amplitude ratio of the signals.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, together with the specification, illustrateexemplary embodiments of the present invention, and, together with thedescription, serve to explain aspects of embodiments of the presentinvention.

FIG. 1 is a diagram showing a pressure detecting system according to anexemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a pressuredetecting system according to an exemplary embodiment of the presentinvention.

FIGS. 3A to 4C are graphs showing an operation of controlling anamplitude ratio of two signals corresponding to pressure applied to atip of a stylus according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a stylus according to anotherexemplary embodiment of the present invention.

FIG. 6 is a flow chart showing a driving method of a pressure detectingsystem according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, certain exemplary embodiments of the present invention willbe described with reference to the accompanying drawings. When a firstelement is described as being coupled to a second element, the firstelement may be directly coupled to the second element, or may beindirectly coupled to the second element via one or more other elements.Further, some elements that are not essential to the completeunderstanding of the embodiments of the present invention are omittedfor clarity. Also, like reference numerals refer to like elementsthroughout.

Specific matters of other exemplary embodiments will be included in thedetailed description and the accompanying drawings. Aspects ofembodiments of the present invention, and methods to achieve suchaspects, will be elucidated from exemplary embodiments described belowin detail with reference to the accompanying drawings. However, thepresent invention is not limited to the exemplary embodiments disclosedbelow, but may be implemented in various different forms. Further, inthe accompanying drawings, portions unrelated to the describedembodiments of the present invention may be omitted to improve adescription of the embodiments of the present invention, and samereference numerals will be used to describe same or similar portionsthroughout the present specification.

Hereinafter, a stylus, a pressure detecting system, and a driving methodthereof will be described with reference to exemplary embodiments of thepresent invention, and to drawings for describing the exemplaryembodiments.

FIG. 1 is a diagram showing a pressure detecting system according to anexemplary embodiment of the present invention. Referring to FIG. 1, thepressure detecting system 1 according to the present embodiment of thepresent invention includes a stylus 100 and a pressure detectingapparatus 200.

The stylus 100 is a device capable of being used to input information bycontact with the pressure detecting apparatus, the stylus 100 being usedin lieu of a user's hand. In addition, the stylus 100 may change anamplitude ratio of two signals emitted from the stylus 100 to enablewriting pressure of the stylus 100 to be detected by the pressuredetecting apparatus 200.

The pressure detecting apparatus 200 may be, for example, a digitizer ora touch screen capable of recognizing information corresponding to aninput (e.g., a predetermined input operation) by the stylus 100, anddetecting a position(s) contacted by the stylus 100 according to aresistive scheme, a capacitive scheme, or the like. In addition, thepressure detecting apparatus 200 may detect the writing pressure of thestylus 100 (e.g., pressure between the stylus and the surface of thepressure detecting apparatus) from the amplitude ratio of the twosignals emitted from the stylus 100.

Aspects of the present embodiment are characterized by the sensing ofthe writing pressure of the stylus 100. Therefore, details of the stylus100 and the pressure detecting apparatus 200 of the present embodimentwill be described below.

FIG. 2 is a block diagram showing a pressure detecting system accordingto an exemplary embodiment of the present invention. Referring to FIG.2, a stylus 100 according to the present embodiment may include apressure detector 120, a first signal generator 130, a second signalgenerator 140, and a controller 150.

The pressure detector 120 may detect pressure applied to the stylus 100.For example, the pressure detector 120 may detect pressure applied to atip 110 of the stylus 100 according to a user's writing operation, oraccording to a user's manipulation of the stylus. The tip 110 may becoupled to the pressure detector 120 to transfer pressure generated in,or exerted on, the tip 110 to the pressure detector 120. The tip 110,which is a part capable of contacting the pressure detecting apparatus100, may protrude from one end of the stylus 100.

Although FIG. 2 shows the pressure detector 120 is configured to detectthe pressure applied to the tip 110 as described above, the pressuredetector 120 may detect other kinds of externally applied pressure to,or on, the stylus 100, in addition to the pressure applied through thetip 110. For example, the pressure detector 120 may detect a strength ofa user's grip on the stylus 100. Therefore, the user controls thestrength of the user's hand gripping the stylus 100, thereby making itpossible to control functions (e.g., a line thickness, a color change,etc.) of the stylus (e.g., by squeezing the stylus 100 harder). In thiscase, for example, the pressure detector 120 may include a variablecapacitor having a capacitance changed by the pressure applied to thestylus 100. In addition, the pressure detector 120 may include avariable coil, or a variable resistance (e.g., a variable resistiveelement), or may include a resonance circuit having at least one of thevariable capacitor, the variable coil, or the variable resistance.

The first signal generator 130 may generate a signal S1 of a firstfrequency, and may change an amplitude of the signal S1 of the firstfrequency according to control of the controller 150.

The second signal generator 140 may generate a signal S2 of a secondfrequency, and may change an amplitude of the signal S2 of the secondfrequency according to the control of the controller 150.

Each of the first and second signal generators 130 and 140 may generatea signal having a fixed frequency, and may emit the signal S1 of thefirst frequency and the signal S2 of the second frequency to the outside(e.g., may externally emit the signals S1 and S2) via a signal emitter(e.g., a single signal emitter) 160. Therefore, a separate component forchanging the frequency may be omitted from within the first and secondsignal generators 130 and 140. In addition, the first and secondfrequencies may be different frequencies.

The controller 150 controls the first signal generator 130 and/or thesecond signal generator 140 corresponding to the pressure detectedthrough the pressure detector 120, thereby making it possible to controlan amplitude ratio between the signal S1 of the first frequency and thesignal S2 of the second frequency. In the present embodiment, thecontroller 150 may change the amplitudes of the signal S1 of the firstfrequency and/or the signal S2 of the second frequency to have anamplitude ratio corresponding to the pressure detected through thepressure detector 120 with reference to a separate lookup table, anequation, or the like.

The pressure detecting apparatus 200 may receive the signal S1 of thefirst frequency and the signal S2 of the second frequency emitted fromthe stylus 100, and may calculate the pressure applied to the stylus 100from the amplitude ratio of the signals S1 and S2. Accordingly, thepressure detecting apparatus 200 may include a receiver 210 and apressure calculator 220.

The receiver 210 may receive the signal S1 of the first frequency andthe signal S2 of the second frequency, which are emitted from the signalemitter 160 of the stylus 100.

The pressure calculator 220 calculates the amplitude ratio of the signalS1 of the first frequency to the signal S2 of the second frequencyreceived by the receiver 210, and inversely transforms the calculatedamplitude ratio, thereby making it possible to calculate the pressureapplied to the stylus 100. In the present embodiment, the pressurecalculator 220 may refer to the separate lookup table or the equation(or may refer to a different lookup table or equation) similar to thecontroller 150 of the stylus 100.

In addition, the pressure calculator 220 may include filters suitable oroptimized for signals of the first frequency and the second frequency todivide the signal received by the receiver 210 into the signal S1 of thefirst frequency and the signal S2 of the second frequency. Therefore,the writing pressure of the stylus 100 may be detected by changing onlythe amplitude of the signals S1 and S2 having the fixed frequencies, andwithout performing a complicated process of changing the frequency ofthe signal.

FIGS. 3A to 4C are graphs showing an operation of controlling anamplitude ratio of two signals according to pressure applied to a tip ofa stylus according to an embodiment of the present invention. FIGS. 3Ato 3C show an operation of controlling an amplitude ratio of the signalsS1 and S2 by changing both of the amplitudes of the signals S1 and S2 ofthe first and second frequencies, and FIGS. 4A and 4C show an operationof controlling an amplitude ratio of the signals S1 and S2 by changingthe amplitude of the signal S1 of the first frequency, while fixing, ornot changing, the amplitude of the signal S2 of the second frequency.

Referring to FIG. 3A, when the pressure applied to the tip 110 of thestylus 100 is detected as ‘A,” and when an amplitude ratio correspondingto the pressure ‘A’ is set to be ‘a1:a2,’ the controller 150 may controlthe signal S1 of the first frequency and the signal S2 of the secondfrequency to respectively be ‘na1’ and ‘na2.’ Therefore, the pressuredetecting apparatus 200 receiving the signal S1 of the first frequencyhaving an amplitude of ‘na1’ and the signal S2 of the second frequencyhaving an amplitude of ‘na2’ may calculate an amplitude ratio (‘a1:a2’)of the signals S1 and S2, and may inversely calculate the ‘Pressure A’applied to the tip 110 from the calculated amplitude ratio.

In addition, referring to FIG. 3B, in the case in which the pressureapplied to the tip 110 of the stylus 100 is changed from ‘A’ to ‘B,’ andwhen the amplitude ratio corresponding to the ‘Pressure B’ is set to be‘b1:b2,’ the controller 150 may change the amplitudes of the signal S1of the first frequency and the signal S2 of the second frequency torespectively be ‘nb1’ and ‘nb2.’ Therefore, the pressure detectingapparatus 200 receiving the signal S1 of the first frequency having theamplitude of ‘nb1’ and the signal S2 of the second frequency having theamplitude of ‘nb2’ may calculate an amplitude ratio (‘b1:b2’) of thesignals S1 and S2, and may inversely calculate the ‘Pressure B’ appliedto the tip 110 from the calculated amplitude ratio.

Further, referring to FIG. 3C, when the stylus 100 is spaced apart from,or not in contact with, the pressure detecting apparatus 200, that is,when the stylus 100 is in a ‘Hovering’ state, the controller 150 may setthe amplitude of the signal S1 of the first frequency to be ‘0.’ Thatis, the generation of the signal S1 of the first frequency may bestopped such that only the signal S2 of the second frequency istransferred to the pressure detecting apparatus 200. Therefore, asituation where the pressure detecting apparatus 200 is receiving onlythe signal S2 of the second frequency may indicate that the stylus 100is in the hovering state.

Referring to FIG. 4A, when the pressure applied to the tip 110 of thestylus 100 is detected as ‘C,’ and when an amplitude ratio correspondingto the ‘Pressure C’ is set to be ‘1:1,’ the controller 150 may controlamplitudes of the signal S1 of the first frequency and the signal S2 ofthe second frequency to be the same as each other. Because the amplitudeof the signal S2 of the second frequency is fixed at, for example,‘nc1,’ the controller 150 might control only the amplitude of the signalS1 of the first frequency to be ‘nc1.’ Therefore, the pressure detectingapparatus 200 receiving the signals S1 and S2 of the first and secondfrequencies having the same amplitude of ‘nc1’ may calculate anamplitude ratio (‘1:1’) of the signals S1 and S2, and may inverselycalculate the ‘Pressure C’ applied to the tip 110 from the calculatedamplitude ratio.

Referring to FIG. 4B, when the pressure applied to the tip 110 of thestylus 100 is changed from ‘C to D,’ and when an amplitude ratiocorresponding to the ‘Pressure D’ is set to be ‘d1:c1,’ the amplitude ofthe signal S2 of the second frequency is fixed at, or set to, ‘nc1.’Therefore, the controller 150 might control only the amplitude of thesignal S1 of the first frequency to be ‘nd1.’ Therefore, the pressuredetecting apparatus 200 receiving the signal S1 of the first frequencyhaving the amplitude of ‘nd1’ and the signal S2 of the second frequencyhaving the amplitude of ‘nc1’ may calculate an amplitude ratio (‘d1:c1’)of the signals S1 and S2, and may inversely calculate the pressure ‘D’applied to the tip 110 from the calculated amplitude ratio.

Referring to FIG. 4C, when the pressure applied to the tip 110 of thestylus 100 is changed from ‘C’ to ‘0’ (that is, when the stylus 100 ischanged to the ‘Hovering’ state), and when an amplitude ratiocorresponding to the pressure ‘0’ is set to be ‘e1:c1,’ the amplitude ofthe signal S2 of the second frequency may be fixed at ‘nc1.’ Therefore,the controller 150 might control, or change, only the amplitude of thesignal S1 of the first frequency to be ‘ne1.’ Therefore, the pressuredetecting apparatus 200 receiving the signal S1 of the first frequencyhaving the amplitude of ‘ne1’ and the signal S2 of the second frequencyhaving the amplitude of ‘nc1’ may calculate an amplitude ratio (‘e1:c1’)of the signals S1 and S2, and may inversely calculate the pressure ‘0’applied to the tip 110 from the calculated amplitude ratio. Because onlythe amplitude of any one of the signal S1 of the first frequency and thesignal S2 of the second frequency is changed, a hardware configurationmay be simplified as compared to changing the amplitudes of both of thesignals S1 and S2.

FIG. 5 is a diagram showing a stylus according to another exemplaryembodiment of the present invention. Referring to FIG. 5, the stylus 200according to another exemplary embodiment may be configured to include afirst signal emitter 161 and a second signal emitter 162. Therefore, thefirst and second signal generators 130 and 140 may respectivelyexternally emit a signal S1 of a first frequency and a signal S2 of asecond frequency through different signal emitters 161 and 162. Forexample, the first signal generator 130 may externally emit the signalS1 of the first frequency through the first signal emitter 161, and thesecond signal generator 140 may externally emit the signal S2 of thesecond frequency through the second signal emitter 162.

Only differences between a configuration of the present embodiment fromthat of the above-mentioned exemplary embodiment have been described,and description of similarities of the two embodiments is omitted.

FIG. 6 is a flow chart showing a driving method of a pressure detectingsystem according to an exemplary embodiment of the present invention.Referring to FIG. 6, the driving method of the pressure detecting systemaccording to the present exemplary embodiment of the present inventionincludes a pressure detecting step (S100); an amplitude ratio changingstep (S200); a signal emitting step (S300), an amplitude ratiocalculating step (S400), and a pressure calculating step (S500).

In the pressure detecting step (S100), pressure applied to the stylus100 is detected. In the present embodiment, pressure applied to the tip110 of the stylus 100 may be detected, and/or pressure applied by gripstrength of a hand gripping the stylus 100 may be detected. Further, thepressure applied to the stylus 100 may be calculated through thepressure detector 120 including a variable capacitor, or the like.

In the amplitude ratio changing step (S200), an amplitude ratio of asignal S1 of a first frequency to a signal S2 of a second frequency ischanged in a manner corresponding to the pressure detected in thepressure detecting step (S100). In the present embodiment, the amplituderatio of the signals S1 and S2 may be controlled by changing any one ofthe signals S1 and S2 or by changing both of the signals S1 and S2. Inaddition, the first and second frequencies of the signals S1 and S2 maybe different from each other.

In the signal emitting step (S300), the signal S1 of the first frequencyand the signal S2 of the second frequency may be externally emitted.Here, the signal S1 of the first frequency and the signal S2 of thesecond frequency may be externally emitted via a single signal emitter160 (as shown in FIG. 2), or may be emitted through different signalemitters 161 and 162 (as shown in FIG. 5).

In the amplitude ratio calculating step (S400), the amplitude ratio ofthe signal S1 of the first frequency to the signal S2 of the secondfrequency, which are received in the pressure detecting apparatus 200,may be calculated.

In the pressure calculating step (S500), the pressure applied to thestylus 100 may be calculated using the amplitude ratio calculated in theamplitude calculating step (S400).

As set forth above, according to exemplary embodiments of the presentinvention, the stylus, the pressure detecting system for detectingwriting pressure of the stylus without changing the frequency of thesignal emitted from the stylus, and the driving method thereof, may beprovided.

While embodiments of the present invention has been described inconnection with certain exemplary embodiments, it is to be understoodthat the invention is not limited to the disclosed embodiments, but, onthe contrary, is intended to cover various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims, and equivalents thereof.

What is claimed is:
 1. A stylus comprising: a pressure detector fordetecting applied pressure; a first signal generator for generating asignal of a first frequency; a second signal generator for generating asignal of a second frequency; and a controller for adjusting at leastone of the first and second signal generators to control an amplituderatio of the signal of the first frequency to the signal of the secondfrequency according to the applied pressure detected by the pressuredetector.
 2. The stylus according to claim 1, wherein the firstfrequency and the second frequency are different from each other.
 3. Thestylus according to claim 1, wherein the first and second signalgenerators are respectively configured to emit the signals of the firstand second frequencies through a single signal emitter.
 4. The stylusaccording to claim 1, wherein the first signal generator and the secondsignal generator respectively emit the signal of the first frequency andthe signal of the second frequency through different signal emitters. 5.The stylus according to claim 1, wherein the controller is configured tochange an amplitude of only one of the signals of the first and secondfrequencies to control the amplitude ratio of the signals of the firstand second frequencies.
 6. The stylus according to claim 1, wherein thecontroller is configured to change both an amplitude of the signal ofthe first frequency and an amplitude of the signal of the secondfrequency to control the amplitude ratio of the signals of the first andsecond frequencies.
 7. A pressure detecting system comprising: a styluscomprising: a pressure detector for detecting applied pressure; a firstsignal generator for generating a signal of a first frequency; a secondsignal generator for generating a signal of a second frequency; and acontroller for adjusting at least one of the first and second signalgenerators to control an amplitude ratio of the signal of the firstfrequency to the signal of the second frequency according to the appliedpressure detected by the pressure detector; and a pressure detectingapparatus for receiving the signals of the first and second frequenciesfrom the stylus, and for detecting the applied pressure according to theamplitude ratio of the signal of the first frequency to the signal ofthe second frequency.
 8. The pressure detecting system according toclaim 7, wherein the first frequency and the second frequency aredifferent from each other.
 9. The pressure detecting system according toclaim 7, wherein the first signal generator and the second signalgenerator respectively emit the signal of the first frequency and thesignal of the second frequency through a single signal emitter.
 10. Thepressure detecting system according to claim 7, wherein the first signalgenerator and the second signal generator respectively emit the signalof the first frequency and the signal of the second frequency throughdifferent signal emitters.
 11. The pressure detecting system accordingto claim 7, wherein the controller is configured to change an amplitudeof only one of the signals of the first and second frequencies tocontrol the amplitude ratio of the signals.
 12. The pressure detectingsystem according to claim 7, wherein the controller is configured tochange both the amplitude of the signal of the first frequency and theamplitude of the signal of the second frequency to control the amplituderatio of the signals.
 13. A driving method of a pressure detectingsystem, the method comprising: detecting applied pressure; controllingan amplitude ratio of a signal of a first frequency to a signal of asecond frequency according to the detected applied pressure; emittingthe signal of the first frequency and the signal of the secondfrequency; receiving the signal of the first frequency and the signal ofthe second frequency; calculating the amplitude ratio of the signal ofthe first frequency to the signal of the second frequency; andcalculating the pressure from the calculated amplitude ratio.
 14. Themethod of claim 13, wherein the first frequency and the second frequencyare different from each other.
 15. The method of claim 13, whereincontrolling the amplitude ratio comprises changing an amplitude of onlyone of the signals of the first and second frequencies to control theamplitude ratio of the signals.
 16. The method of claim 13, whereincontrolling the amplitude ratio comprises changing both an amplitude ofthe signal of the first frequency and an amplitude of the signal of thesecond frequency to control the amplitude ratio of the signals.